The disclosed subject matter relates to methods and apparatus for controlling a variable-displacement, multiple-cylinder, internal combustion engine. More particularly, the disclosed subject matter relates to varying the displacement by selectively deactivating combustion in one or more cylinders of the engine.
Some related art internal combustion engines can include a relatively large number of combustion cylinder assemblies in order to achieve one or more desirable performance targets, such as but not limited to high travel speed, low acceleration times, high torque output at low speeds, etc. Generally, fuel efficiency of an engine with a larger number of combustions cylinders can be less than that for an engine having a smaller number of combustion cylinder assemblies. Additionally, the total torque output by the engine can exceed the amount necessary under certain operating conditions, such as idling, low speed travel, heavy traffic, etc. This excess torque can be converted to heat exhausted to the ambient environment, thus further reducing the fuel efficiency of the engine.
In order to enhance or improve fuel efficiency under low load conditions, some related art multiple-cylinder engines can selectively deactivate combustion in one or more cylinders of the engine. For example, a six-cylinder engine can be operated in a four-cylinder mode or in a three-cylinder mode. Similarly, an eight-cylinder engine can be operated in one of at least six-a cylinder mode and a four-cylinder mode.